Free rotation endpoint and champions endpoint deprecation

[Colorfulstan]

New Free rotation endpoint live now, deprecation of /platform/champions + /platform/champions/by-id on October 15th

https://discussion.developer.riotgames.com/articles/6035/free-champion-rotation-endpoint.html

• [ ] add new endpoint
• [ ] deprecate other endpoints ( are they even in? Never used it I think))